Lubricant for two-stroke cycle engines

ABSTRACT

A lubricant composition adapted for a two stroke cycle engine comprises 5 wt. % to 35 wt. % of an oil of lubricating viscosity, greater than 50 wt. % to 90 wt. % of a hydrocarbon solvent and at least one additive selected from (i) a dispersant and (ii) a friction modifier.

BACKGROUND OF THE INVENTION

The disclosed technology relates to an engine lubricant, particularly for two-stroke cycle engines, and to combustible compositions for fueling two-stroke cycle engines.

Two-stroke cycle engines are widely used for portable power equipment and also represent an important portion of the engines used in transportation, particularly in the developing regions of the world. The lubricants required for the operation of two-stroke cycle engines are, in some designs, mixed with the liquid fuel, and this fuel-lubricant mixture is typically passed through the crankcase and, ultimately, to the combustion chambers, where the entire fuel-lubricant composition is burned. Combustion of the lubricant can generate high particulate emissions. The particulate emissions emanating from conventional two-cycle fuel-lubricant combustion generally comprise organic carbon particulates of various sizes and number profiles. As global constraints on particulate emissions become tighter, the use of two-cycle engines may come under increasing scrutiny. One approach to complying with tighter emissions demands is to reduce the use and reliance on two-cycle engines. An alternative approach is to employ rather expensive catalysts to react with and reduce particle emissions. As noted, the use of catalysts can add cost to engine manufacture and operation and are susceptible to degradation by ash-containing additives in lubricant compositions. It would, therefore, be desirable to provide lubricant compositions and fuel-lubricant mixtures that, during operation of two-cycle engines lubricated and fueled, respectively, thereby, generate reduced particulate emissions, in relation to one of at least reduced particulate mass, total organic or elemental carbon, or particle number, and preferably more than one of reduced particulate mass, total organic or elemental carbon, or particle number, while maintaining engine performance, lubricity, and cleanliness.

SUMMARY OF THE INVENTION

The disclosed technology provides a lubricant composition comprising:

-   -   a. 5 wt. % to 35 wt. % of an oil of lubricating viscosity,     -   b. greater than 50 wt. % to 90 wt. % of a hydrocarbon solvent;         and     -   c. at least one additive selected from (i) a dispersant and (ii)         a friction modifier.

In some embodiments, the lubricant composition may comprise 5 to 25 wt. %, or 5 to 20 wt. %, or 5 to 15 wt. %, or 5 to 10 wt. % of an oil of lubricating viscosity.

In some embodiments, the oil of lubricating viscosity may be selected from any of a Group I, II, III, IV or V base oil and blends thereof.

In still further embodiments, a lubricant composition may comprise 60 to 90 wt. %, or 65 to 90 wt. % of a hydrocarbon solvent.

In certain embodiments, the hydrocarbon solvent may be selected from one or more of aromatic type hydrocarbon solvents, aliphatic type hydrocarbon solvents, naphthenic type hydrocarbon solvents or various blends thereof.

The hydrocarbon solvent in certain embodiments may have a boiling point of between about 140° C. (284° F.) and about 350° C. (662° F.). The hydrocarbon solvent in certain embodiments may have a flash point of between about 40° C. (104° F.) and about 140° C. (284° F.).

In some embodiments, the dispersant may include a Mannich-type dispersant and a succinimide-type dispersant.

In some embodiments, the weight percent ratio of dispersant to oil of lubricating viscosity may be 1:6 to 1:2.5.

The disclosed technology further provides a combustible mixture for fueling a two-cycle engine comprising a lubricating composition admixed with a liquid fuel composition at a ratio of 1:60 to 1:40, or about 1:50 by volume, wherein the lubricating composition comprises:

a. from 5 wt. % to 35 wt. % of an oil of lubricating viscosity,

b. from 60 wt. % to 90 wt. of a hydrocarbon solvent;

c. from 0.02 wt. % to 10 wt. % of a dispersant

d. from 0.1 wt. % to 5 wt. % of at least one friction modifier, and

e. optionally, a detergent.

The disclosed technology also provides a method of lubricating an internal combustion engine, such as a two-stroke cycle engine, comprising supplying thereto the lubricant composition.

The disclosed technology also provides a method of fueling an internal combustion engine, such as a two-stroke cycle engine, comprising supplying thereto the combustible mixture.

DETAILED DESCRIPTION OF THE INVENTION

Various preferred features and embodiments will be described below by way of non-limiting illustration.

One component of the disclosed technology, which in all instances of the present invention will be a minor portion of the lubricant composition, is an oil of lubricating viscosity, which may be referred to as a base oil. The base oil may be selected from any of the base oils in Groups I-V of the American Petroleum Institute (API) Base Oil Interchangeability Guidelines, namely

Base Oil Category Sulfur (%) Saturates (%) Viscosity Index Group I >0.03 and/or <90 80 to 120 Group II ≤0.03 and ≥90 80 to 120 Group III ≤0.03 and ≥90 >120 Group IV All polyalphaolefins (PAOs) Group V All others not included in Groups I, II, III or IV

Groups I, II and III are mineral oil base stocks. The oil of lubricating viscosity can include natural or synthetic oils and mixtures thereof. Mixtures of mineral oil and synthetic oils, e.g., polyalphaolefin oils and/or polyester oils, may be used. In some embodiments of the present invention, the base oil will be a Group I, II, or III base oil, and in some embodiments it will be a mixture of base oils comprising a Group I, II, or III base oil and at least one of a Group IV or V oil. In some embodiments, the base oil may be substantially free of a Group I, or Group II or Group III or Group IV or Group V base oil.

Natural oils include animal oils and vegetable oils (e.g. vegetable acid esters) as well as mineral lubricating oils such as liquid petroleum oils and solvent-treated or acid treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Hydrotreated or hydrocracked oils are also useful oils of lubricating viscosity. Oils of lubricating viscosity derived from coal or shale are also useful.

Synthetic oils include hydrocarbon oils and halosubstituted hydrocarbon oils such as polymerized and interpolymerized olefins and mixtures thereof, alkylbenzenes, polyphenyl, alkylated diphenyl ethers, and alkylated diphenyl sulfides and their derivatives, analogs and homologues thereof. Alkylene oxide polymers and interpolymers and derivatives thereof, and those where terminal hydroxyl groups have been modified by, e.g., esterification or etherification, are other classes of synthetic lubricating oils.

Other suitable synthetic lubricating oils include esters of dicarboxylic acids and those made from C₅ to C₁₂ monocarboxylic acids and polyols or polyol ethers. More specifically, esters useful as synthetic oils may comprise esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, and alkenyl malonic acids) with any of a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Further, esters useful as synthetic oils may also include those made from C5 to C20 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol.

Still other synthetic lubricating oils may include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, silicon-based oils such as poly-alkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils, and silicate oils.

Other synthetic oils include those produced by Fischer-Tropsch reactions, typically hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment oils may be prepared by a Fischer-Tropsch gas-to-liquid synthetic procedure as well as other gas-to-liquid oils.

Unrefined, refined and rerefined oils, either natural or synthetic (as well as mixtures thereof) of the types disclosed hereinabove can be used. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Rerefined oils often are additionally processed to remove spent additives and oil breakdown products.

The base oils, and particularly the synthetic ester oils, will typically have a kinematic viscosity at 100° C. (KV 100) of at least 2.7 mm²s⁻¹ (cSt) (or at least 3 cSt) (or at least 6 cSt). Base oils may typically have a boiling point in the range of about 350° C. to about 800° C. and/or a flash point greater than about 150° C.

In all embodiments of the lubricant compositions, the total base oil, namely, the total of all Group I-V oils in the lubricant composition, will constitute a minor portion (less than 50 percent by weight (also referred to as wt. %)) of the lubricant composition, with a major portion (greater than 50 wt. %) of the lubricant being a solvent (as discussed in further detail below). In fact, particularly useful lubricating compositions demonstrating excellent performance with low particulate emissions may have a total amount of oil of lubricating viscosity (including diluent or carrier oils present in the additional components referenced below) of less than 35 wt. %, or less than 25 wt. % or 20 wt. %, or even less than 15 wt. % or 10 wt. % of the lubricant composition. In some embodiments, the total amount of oil of lubricating viscosity may be from 5 to 35 wt. % or 5 to 25 wt. % or 5 to 20 wt. % or 5 to 15 wt. % of the lubricant composition.

A second component of the lubricant composition is a solvent. The solvent is typically a hydrocarbonaceous (or hydrocarbon) solvent, that is, one which exhibits principally hydrocarbon character, even though relatively small numbers of heteroatoms may be present in the molecule. The solvent may be a hydrocarbon and may have predominantly aromatic character or non-aromatic (e.g., alkane) character. The solvent may comprises less than 20 percent by weight aromatic components and/or may be substantially free from polynuclear aromatic components.

The solvent may be characterized by a KV 100 of less than 2.5 cSt, or less than 2.0 or 1.5 or 1.0 cSt. Particularly useful are solvents having a boiling point range of about 140° C. (284° F.) to about 350° C. (662° F.). The hydrocarbon solvent in certain embodiments may have a flash point of between about 40° C. (104° F.) and about 140° C. (284° F.).

Examples of useful solvents may include kerosene, hydrotreated kerosene, middle distillate fuels, isoparaffinic and naphthenic aliphatic hydrocarbon solvents, dimers, and higher oligomers of propylene butene and similar olefins as well as paraffinic and aromatic hydrocarbon solvents and mixtures thereof. Such solvents may contain functional groups other than carbon and hydrogen and may include alcohols, esters, ethers, ketones, and aldehyde solvents and blends thereof. Alcohol solvents may include such alcohols as methanol, ethanol and butanol. Particularly useful are aliphatic solvents, including the solvent sold under the trademark “Exxsol D80®” by Exxon Chemical Company.

As referenced above, the solvent or solvent blend will constitute the major portion of the lubricant compositions. The amount of solvent in a fully formulated lubricant of the disclosed technology will, accordingly, be greater than 50 wt. %, or, in some embodiments, greater than 60 wt. % or 70 wt. %, or even 80 wt. % or 90 wt. % of the lubricant composition. In some embodiments, the amount of hydrocarbon solvent will be from greater than 50 wt. % to 95 wt. % or 60 wt. % to 90 wt. % or 70 wt. % to 90 wt. % or 75 wt. % to 90 wt. %.

In other embodiments, the ratio of solvent to total base oil in the lubricant composition may be from 15:1 to 1.5:1 or 15:1 to 2:1 or 15:1 to 4:1 or 15:1 to 6:1.

The lubricating compositions of the present invention will include at least one dispersant. Dispersants in general are well known in the field of lubricants and include primarily what are known as ashless dispersants and polymeric dispersants. Ashless dispersants are so-called because, as supplied, they do not contain metal and thus do not normally contribute to sulfated ash when added to a lubricant. However they may, of course, interact with ambient metals if they are added to a lubricant which includes metal-containing species. Ashless dispersants are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain.

The lubricant compositions of the present invention may include at least one of a Mannich-type dispersant, a succinimide-type dispersant or a phenolic-type dispersant. In some embodiments, the lubricant may include a Mannich-type and a succinimide-type dispersant. In still other embodiments, the lubricant may include a Mannich-type and a succinimide-type and a phenolic-type dispersant.

A Mannich-type dispersant, which may also be referred to herein as a Mannich dispersant, is a reaction product of a hydrocarbyl-substituted phenol, an aldehyde, and an amine or ammonia. The hydrocarbyl substituent of the hydrocarbyl-substituted phenol can have 10 to 400 carbon atoms, in another instance 30 to 180 carbon atoms, and in a further instance 10 or 40 to 110 carbon atoms. This hydrocarbyl substituent can be derived from an olefin or a polyolefin. Useful olefins include alpha-olefins and branched alpha-olefins, such as ethylene, propylene, isobutylene, 1-butene, 1-decene, etc. which are commercially available.

Useful polyolefins which can form the hydrocarbyl substituent can be prepared, for instance, by polymerizing olefin monomers by well-known polymerization methods and are also commercially available. The olefin monomers include monoolefins, including monoolefins having 2 to 10 carbon atoms such as ethylene, propylene, 1-butene, isobutylene, and 1-decene. An especially useful monoolefin source is a C4 refinery stream having a 35 to 75 weight percent butene content and a 30 to 60 weight percent isobutene content. Useful olefin monomers also include diolefins such as isoprene and 1,3-butadiene. Olefin monomers can also include mixtures of two or more monoolefins, of two or more diolefins, or of one or more monoolefins and one or more diolefins. Useful polyolefins include polyisobutylenes having a number average molecular weight of 140 to 5000, in another instance of 400 to 2500, and in a further instance of 140 or 500 to 1500. The polyisobutylene can have a vinylidene double bond content of 5 to 69%, in a second instance of 50 to 69%, and in a third instance of 50 to 95%. The polyolefin can be a homopolymer prepared from a single olefin monomer or a copolymer prepared from a mixture of two or more olefin monomers. Also possible as the hydrocarbyl substituent source are mixtures of two or more homopolymers, two or more copolymers, or one or more homopolymers and one or more copolymers. The foregoing description of suitable hydrocarbyl groups or polyolefin groups is also applicable to the hydrocarbyl substituent of the succinimide dispersant, described in detail below.

The hydrocarbyl-substituted phenol which is used to prepare the Mannich dispersant can be prepared by alkylating phenol with an olefin or polyolefin described above, such as a polyisobutylene or polypropylene, using well-known alkylation methods.

The aldehyde used to form the Mannich dispersant can have 1 to 10 carbon atoms, and is generally formaldehyde or a reactive equivalent thereof such as formalin or paraformaldehyde.

The amine used to form the Mannich dispersant can be a monoamine or a polyamine, including alkylene polyamine, other aliphatic and aromatic mono- and polyamines, alkanolamines having one or more hydroxyl groups and mixtures thereof. Useful amines include ethanolamine, diethanolamine, methylamine, dimethylamine, ethylenediamine, dimethyl aminopropylamine, diethylenetriamine and 2-(2-aminoethyl-amino)ethanol. The Mannich dispersant can be prepared by reacting a hydrocarbyl-substituted phenol, an aldehyde, and an amine as described in U.S. Pat. No. 5,697,988. In one embodiment, the Mannich reaction product is prepared from an alkylphenol derived from a polyisobutylene, formaldehyde, and an amine that is a primary monoamine, a secondary monoamine, or an alkylenediamine, in particular, ethylenediamine or dimethylamine. In one embodiment, the alkylphenol may be prepared from a high-vinylidene polyisobutene, having, e.g., greater than 50, greater than 70 or greater than 75 percent terminal vinylidene groups (i.e., such percentage of polyisobutylene molecules having vinylidene end groups; that is, mole percentage of polyisobutylene molecules having a terminal vinylidene group.) The foregoing description of the amine is also applicable to the description of the amine used in preparing the succinimide dispersant, described below.

In one embodiment the Mannich dispersant comprises the reaction product of a hydrocarbyl-substituted phenol, formaldehyde or a reactive equivalent of formaldehyde, and a primary or secondary amine. In one embodiment the Mannich dispersant comprises the reaction product of a polyisobutene-substituted phenol, formaldehyde or a reactive equivalent of formaldehyde, and dimethylamine.

The amount of the Mannich dispersant employed in the lubricant composition may be in the range of 0.1 to 5 wt. % of the lubricant composition. In other embodiments it may be present at 0.15 to 3.0 wt. %, or 0.2 to 3.0 wt. %, or 0.5 to 3.0 wt. %, or 1.0 to 2.0 wt. % of the lubricant composition.

A second type of dispersant that may be present in the lubricant compositions is a succinimide-type dispersant. In one embodiment, the succinimide dispersant is a condensation product of hydrocarbyl-substituted succinic anhydride or a reactive equivalent thereof (e.g., an anhydride, ester, or acid halide), with a polyethylene polyamine. Succinimide dispersants may generally be viewed as comprising a variety of chemical structures including typically

where each R¹ is independently an alkyl group, frequently a polyisobutylene group with a molecular weight (M_(n)) of 500-5000 based on the polyisobutylene precursor, and R² are alkylene groups, commonly ethylene (C₂H₄) groups. Such molecules are commonly derived from reaction of an alkenyl acylating agent with a polyamine, and a wide variety of linkages between the two moieties is possible beside the simple imide structure shown above, including a variety of amides and quaternary ammonium salts. In the above structure, the amine portion is shown as an alkylene polyamine, although other aliphatic and aromatic mono- and polyamines may also be used. Also, a variety of modes of linkage of the R¹ groups onto the imide structure are possible, including various cyclic linkages. The ratio of the carbonyl groups of the acylating agent to the nitrogen atoms of the amine may be 1:0.5 to 1:3, and in other instances 1:1 to 1:2.75 or 1:1.5 to 1:2.5. Succinimide dispersants are more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892 and in EP 0355895.

Succinimide dispersants may also be described as being prepared from hydrocarbyl-substituted succinic acylating agent which are, in turn, prepared by the so-called “chlorine” route or by the so-called “thermal” or “direct alkylation” route. These routes are described in detail in published application US 2005-0202981, paragraphs 0014 through 0017. A direct alkylation or low-chlorine route is also described in U.S. Pat. No. 6,077,909; refer to column 6 line 13 through col. 7 line 62 and column 9 lines 10 through col. 10 line 11. Illustrative thermal or direct alkylation processes involve heating a polyolefin, typically at 180 to 250° C., with maleic anhydride under an inert atmosphere. Either reactant may be in excess. If the maleic anhydride is present in excess, the excess may be removed after reaction by distillation. These reactions may employ, as the polyolefin, high vinylidene polyisobutylene, that is, having greater than 50, 70, or 75% terminal vinylidene groups (α and β isomers). In certain embodiments, the succinimide dispersant may be prepared by the direct alkylation route. In other embodiments it may comprise a mixture of direct alkylation and chlorine-route dispersants.

The succinimide dispersant will be one which is capable of providing a relatively large quantity of nitrogen to the lubricant. The nitrogen will be nitrogen atoms that are a part of the amine component or the condensed amide or imide groups of the dispersant. That is, it will impart at least 40 parts per million by weight of nitrogen to the lubricant, and in some embodiments at least 70 or 100 or 130 or 150 parts per million, and up to, for example, 1000 or 900 or 800 or 600 parts per million. These amounts will be determined by both the amount of the succinimide dispersant in the lubricant formulation and the amount of nitrogen within the given dispersant. Thus, certain of the succinimide dispersants of the present technology are comparatively high in nitrogen content, i.e., at least 3 wt. % of the succinimide dispersant or at least 4 wt. % or at least 4.4 wt. %, and up to 6 or 5.5 or 5 wt. %.

Such high nitrogen dispersants are, in certain embodiments, characterized as having a basicity, which may be referred to as base number or total base number (TBN) according to ASTM D2896, due to the presence of basic amine functionality. The present succinimide dispersant may thus have a TBN of at least 90 or 100 or 110 and up to, for instance, 160 or 140 or 120. Other suitable TBN ranges may be 60 to 160 or 70 to 140 or 80 to 120. Such values are to be calculated on the basis of an oil-free dispersant, as will be evident to the skilled person. In certain applications, the succinimide dispersant may be borated.

The amount of the succinimide dispersant employed in the lubricant composition may be in the range of 0.1 to 5 wt. % of the lubricant composition. In other embodiments it may be present at 0.15 to 3.0 wt. %, or 0.2 to 3.0 wt. %, or 0.5 to 3.0 wt. %, or 1.0 to 2.0 wt. %.

The combined amount of the Mannich dispersant and the succinimide dispersant may be in the range of 0.2 to 10 wt. % of the lubricant composition. In other embodiments, 0.5 to 10 wt. %, or 1 to 8 wt. %, or 2 to 6 wt. %, or 2 to 5 wt. %. The relative amounts of the Mannich dispersant and the succinimide dispersant, expressed as a weight ratio, may be 80:20 to 20:80 or alternatively 70:30 to 30:70 or 65:35 to 45:55.

Other dispersants may also be present, if desired. They may be lower nitrogen-content dispersants than the above-described succinimide dispersant, or they may have shorter or longer hydrocarbyl chains, or they may have other functional groups. One such dispersant may be a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent, such as a fatty acid, with an amine. The fatty acid may contain 10 to 26 carbon atoms (e.g., 12 to 24 or 14 to 20 or 16 to 18). An example is isostearic acid. The amine may be a polyethylene polyamine such as tetraethylene pentamine (TEPA). The condensation product may be an amide or an imidazoline. Other dispersants include high molecular weight esters. These materials are similar to the above-described succinimides except that they may be seen as having been prepared by reaction of a hydrocarbyl acylating agent and a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol. Other dispersants include polymeric dispersant additives, also referred to as dispersant viscosity modifiers, which are generally hydrocarbon-based polymers containing polar functionality to impart dispersancy characteristics to the polymer.

Either one or both or all of the dispersants may be post-treated with any of a variety of agents to impart desirable properties thereto, while retaining, in some embodiments, a relatively high TBN for the succinimide dispersant. Such post-treatment includes reaction with urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds such as boric acid, phosphorus compounds, or mixtures thereof. References detailing such treatment are listed in U.S. Pat. No. 4,654,403.

When present, these other dispersants may be present in amounts from 0.01 wt. % to about 2 wt. %.

In certain embodiments of the present invention, lubricant compositions may have a ratio of total dispersant to total base oil (from all component sources in the lubricant composition) of from 1:6 to 1:2.5.

The lubricating compositions of the present invention may further comprise at least one friction modifier, which may be an ashless or ash containing friction modifier. Ashless and ash-containing friction modifiers are well known to those skilled in the art. A useful list of friction modifiers are included in U.S. Pat. No. 4,792,410. U.S. Pat. No. 5,110,488 discloses metal salts of fatty acids and especially zinc salts, useful as friction modifiers. A list of friction modifiers includes fatty acid amides, fatty epoxides, borated fatty epoxides, fatty amines, glycerol esters, borated glycerol esters, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, sulfurized olefins, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines, amide, ester or imide derivatives of hydroxy-carboxylic acids, metal salts of alkyl salicylates, amine salts of alkylphosphoric acids and mixtures thereof.

Representatives of each of these types of friction modifiers are known and are commercially available.

Borated fatty epoxides are known from Canadian Patent No. 1,188,704. These oil-soluble boron containing compositions are prepared by reacting at a temperature from about 80° C. to about 250° C., at least one of boric acid or boron trioxide with at least one fatty epoxide having the formula

wherein each of R¹, R², R³ and R⁴ is hydrogen or an aliphatic radical, or any two thereof together with the epoxy carbon atom or atoms to which they are attached, form a cyclic radical. The fatty epoxide preferably contains at least 8 carbon atoms.

The borated fatty epoxides can be characterized by the method for their preparation which involves the reaction of two materials. Reagent A can be boron trioxide or any of the various forms of boric acid including metaboric acid (HBO₂), orthoboric acid (H₃BO₃) and tetraboric acid (H₂B₄O₇). Boric acid, and especially orthoboric acid, is preferred. Reagent B can be at least one fatty epoxide having the above formula. In the formula, each of the R groups is most often hydrogen or an aliphatic radical with at least one being a hydrocarbyl or aliphatic radical containing at least 6 carbon atoms. The molar ratio of reagent A to reagent B is generally 1:0.25 to 1:4. Ratios of 1:1 to 1:3 are preferred, with about 1:2 being an especially preferred ratio. The borated fatty epoxides can be prepared by merely blending the two reagents and heating them at temperature of 80° to 250° C., preferably 100° to 200° C., for a period of time sufficient for reaction to take place. If desired, the reaction may be effected in the presence of a substantially inert, normally liquid organic diluent. During the reaction, water is evolved and may be removed by distillation.

Non-borated fatty epoxides, corresponding to “Reagent B” above, are also useful as friction modifiers.

Borated amines are generally known from U.S. Pat. No. 4,622,158. Borated amine friction modifiers (including borated alkoxylated fatty amines) are conveniently prepared by the reaction of a boron compounds, as described above, with the corresponding amines. The amine can be a simple fatty amine or hydroxy containing tertiary amines.

The borated amines can be prepared by adding the boron reactant, as described above, to an amine reactant and heating the resulting mixture at a 50° to 300° C., preferably 100° C. to 250° C. or 150° C. to 230° C., with stirring. The reaction is continued until byproduct water ceases to evolve from the reaction mixture indicating completion of the reaction.

Among the amines useful in preparing the borated amines are commercial alkoxylated fatty amines known by the trademark “ETHOMEEN” and available from Akzo Nobel. Representative examples of these ETHOMEEN™ materials is ETHOMEEN™ C/12 (bis[2-hydroxyethyl]cocoamine); ETHOMEEN™ C/20 (polyoxyethylene[10]cocoamine); ETHOMEEN™ S/12 (bis[2-hydroxyethyl]soyamine); ETHOMEEN™ T/12 (bis[2-hydroxyethyl]tallowamine); ETHOMEEN™ T/15 (polyoxyethylene-[5]tallowamine); ETHOMEEN™ 0/12 (bis[2-hydroxyethyl]oleyl-amine); ETHOMEEN™ 18/12 (bis[2-hydroxyethyl]octadecyl amine); and ETHOMEEN™ 18/25 (polyoxyethylene[15]octadecyl amine). Fatty amines and ethoxylated fatty amines are also described in U.S. Pat. No. 4,741,848.

The alkoxylated fatty amines, and fatty amines themselves (such as oleylamine) are generally useful as friction modifiers in this invention. Such amines are commercially available.

Both borated and unborated fatty acid esters of glycerol can be used as friction modifiers. The borated fatty acid esters of glycerol are prepared by borating a fatty acid ester of glycerol with boric acid with removal of the water of reaction. Preferably, there is sufficient boron present such that each boron will react with from 1.5 to 2.5 hydroxyl groups present in the reaction mixture. The reaction may be carried out at a temperature in the range of 60° C. to 135° C., in the absence or presence of any suitable organic solvent such as methanol, benzene, xylenes, toluene, or oil.

Fatty acid esters of glycerol themselves can be prepared by a variety of methods well known in the art. Many of these esters, such as glycerol monooleate and glycerol tallowate, are manufactured on a commercial scale. The useful esters are oil-soluble and are preferably prepared from C₈ to C₂₂ fatty acids or mixtures thereof such as are found in natural products and as are described in greater detail below. Fatty acid monoesters of glycerol are preferred, although, mixtures of mono and diesters may be used. For example, commercial glycerol monooleate may contain a mixture of 45% to 55% by weight monoester and 55% to 45% diester.

Fatty acids can be used in preparing the above glycerol esters; they can also be used in preparing their metal salts, amides, and imidazolines, any of which can also be used as friction modifiers. Preferred fatty acids are those containing 6 to 24 carbon atoms, preferably 8 to 18. The acids can be branched or straight-chain, saturated or unsaturated. Suitable acids include 2-ethylhexanoic, decanoic, oleic, stearic, isostearic, palmitic, myristic, palmitoleic, linoleic, lauric, and linolenic acids, and the acids from the natural products tallow, palm oil, olive oil, peanut oil, corn oil, and Neat's foot oil. A particularly preferred acid is oleic acid. Preferred metal salts include zinc and calcium salts. Examples are overbased calcium salts and basic oleic acid-zinc salt complexes which can be represented by the general formula Zn₄Oleate₃O₁. Preferred amides are those prepared by condensation with ammonia or with primary or secondary amines such as diethylamine and diethanolamine. Fatty imidazolines are the cyclic condensation product of an acid with a diamine or polyamine such as a polyethylenepolyamine. The imidazolines are generally represented by the structure

where R is an alkyl group and R′ is hydrogen or a hydrocarbyl group or a substituted hydrocarbyl group, including —(CH₂CH₂NH)_(n)— groups. In a preferred embodiment the friction modifier is the condensation product of a C₈ to C₂₄ fatty acid with a polyalkylene polyamine, and in particular, the product of isostearic acid with tetraethylenepentamine. The condensation products of carboxylic acids and polyalkyleneamines may generally be imidazolines or amides.

Sulfurized olefins may be used as friction modifiers. A particularly preferred sulfurized olefin is one which is prepared in accordance with the detailed teachings of U.S. Pat. Nos. 4,957,651 and 4,959,168. Described therein is a cosulfurized mixture of two or more reactants selected from the group consisting of (1) at least one fatty acid ester of a polyhydric alcohol, (2) at least one fatty acid, (3) at least one olefin, and (4) at least one fatty acid ester of a monohydric alcohol.

Reactant (3), the olefin component, comprises at least one olefin. This olefin is preferably an aliphatic olefin, which usually will contain 4 to 40 carbon atoms, preferably from 8 to 36 carbon atoms. Terminal olefins, or alpha-olefins, are preferred, especially those having from 12 to 20 carbon atoms. Mixtures of these olefins are commercially available, and such mixtures are contemplated for use in this invention.

The cosulfurized mixture of two or more of the reactants, is prepared by reacting the mixture of appropriate reactants with a source of sulfur. The mixture to be sulfurized can contain 10 to 90 parts of reactant (1), or 0.1 to 15 parts by weight of reactant (2); or 10 to 90 parts, often 15 to 60 parts, more often 25 to 35 parts by weight of reactant (3), or 10 to 90 parts by weight of reactant (4). The mixture, in the present invention, includes reactant (3) and at least one other member of the group of reactants identified as reactants (1), (2) and (4). The sulfurization reaction generally is effected at an elevated temperature with agitation and optionally in an inert atmosphere and in the presence of an inert solvent. The sulfurizing agents useful in the process of the present invention include elemental sulfur, which is preferred, hydrogen sulfide, sulfur halide, sodium sulfide and a mixture of hydrogen sulfide and sulfur or sulfur dioxide. Typically often 0.5 to 3 moles of sulfur are employed per mole of olefinic bonds.

Metal salts of alkyl salicylates include calcium and other salts of long chain (e.g. C12 to C16) alkyl-substituted salicylic acids.

Friction modifiers may include derivatives of (or a compound derived from) a hydroxy-carboxylic acid, prepared or preparable by reaction of the acid group and/or the alcohol group of the hydroxy-carboxylic acids to form esters, amides, and imides and mixtures of multiple such functionalities.

Suitable hydroxy-carboxylic acids may include monohydroxy monocarboxylic acids, polyhydroxy monocarboxylic acids, monohydroxy polycarboxylic acids and polyhydroxy polycarboxylic acids and may be exemplified by citric acid, tartaric acid, lactic acid, malic acid, glycolic acid, hydroxy-propionic acid, hydroxyglutaric acid, oligomers thereof, or mixtures thereof. The derivative of (or compound derived from) a hydroxy-carboxylic acid includes amide, ester or imide derivatives of a hydroxy-carboxylic acid, or mixtures thereof. Typically, the derivative of a hydroxy-carboxylic acid may be a derivative of a hydroxy-polycarboxylic acid such as tartaric acid.

In one embodiment the amide, ester or imide derivative of a hydroxy-carboxylic acid may be at least one of hydroxy-carboxylic acid di-ester, a hydroxy-carboxylic acid di-amide, a hydroxy-carboxylic acid mono-imide, a hydroxy-carboxylic acid di-imide, a hydroxy-carboxylic acid ester-amide, a hydroxy-carboxylic acid ester-imide, and a hydroxy-carboxylic acid imide-amide. In one embodiment the amide, ester or imide derivative of a hydroxy-carboxylic acid may be at least one of the group consisting of a hydroxy-carboxylic acid di-ester, a hydroxy-carboxylic acid di-amide, and a hydroxy-carboxylic acid ester-amide.

Examples of a suitable a hydroxy-carboxylic acid include In one embodiment the amide, ester or imide derivative of a hydroxy-carboxylic acid may be derived from tartaric acid, citric acid, hydroxy-succinic acid, dihydroxy mono-acids, mono-hydroxy diacids, or mixtures thereof. In one embodiment the amide, ester or imide derivative of a hydroxy-carboxylic acid includes a derivative or (or compound derived from) tartaric acid or citric acid. In one embodiment the amide, ester or imide derivative of a hydroxy-carboxylic acid includes a compound derived from tartaric acid.

The derivative of a hydroxy-carboxylic acid may be selected from the group consisting of a hydroxy-carboxylic acid di-ester, a hydroxy-carboxylic acid di-amide, a hydroxy-carboxylic acid imide, a hydroxy-carboxylic acid di-imide, a hydroxy-carboxylic acid ester-amide, a hydroxy-carboxylic acid ester-imide, and a hydroxy-carboxylic acid imide-amide. The derivative of a hydroxy-carboxylic acid may be selected from the group consisting of a hydroxy-carboxylic acid imide, a hydroxy-carboxylic acid di-imide, a hydroxy-carboxylic acid ester-imide, and a hydroxy-carboxylic acid imide-amide.

The derivative of a hydroxy-carboxylic acid may be selected from the group consisting of a hydroxy-carboxylic acid imide and a hydroxy-carboxylic acid di-imide.

The derivative of a hydroxy-carboxylic acid may be derivative of tartaric acid, an imide derivative of citric acid, or mixtures thereof.

The derivative of a hydroxy-carboxylic acid may be imide derivative of tartaric acid, an imide derivative of citric acid, or mixtures thereof. In one embodiment the derivative of a hydroxy-carboxylic acid is either an ester or imide. The ester derivative of a hydroxy-carboxylic acid may be a tartrate. The imide derivative of a hydroxy-carboxylic acid may be a taltrimide.

In one embodiment the derivative of (or compound derived from) a hydroxy-carboxylic acid may be imide derivative of a hydroxy-carboxylic acid. U.S. Patent Application U.S. 60/939,949 (filed May 24, 2007), now WO2008/147704, and U.S. 60/939,952 (filed May 24, 2007), now WO 2008/147700, disclose suitable hydroxy-carboxylic acid compounds, and methods of preparing the same.

Canadian Patent 1 183 125; US Patent Publication numbers 2006/0183647 and US-2006-0079413; U.S. Patent Application No. 60/867,402 (now WO2008/067259); and British Patent 2 105 743 A, all disclose examples of suitable tartaric acid derivatives.

The amount of the friction modifier employed in the lubricant composition may be in the range of 0.1 to 5 wt. % of the lubricant composition. In other embodiments it may be present at 0.15 to 3.0 wt. %, or 0.2 to 3.0 wt. %, or 0.5 to 3.0 wt. %, or 1.0 to 2.0 wt. % of the lubricant composition.

In some embodiments of the present invention, mixtures of ash containing and ashless friction modifiers may be employed. In some embodiments, the lubricant composition may be substantially free of ashless friction modifiers. In yet other embodiments, the lubricant composition may be substantially free of ash-containing friction modifiers.

The lubricant composition may also contain a polymer such as an olefin polymer, as for example polyisobutene. Generally suitable polymers are relatively low molecular weight materials, having a molecular weight (number average) of 5000 or less, such as 500 to 3000 or 1000 to 2500. Occasionally, however, higher molecular weight olefin polymers have been used in two-cycle lubricants; see, for example, U.S. Pat. No. 5,741,764. Such polymers may be hydrogenated to remove most or all of any remaining ethylenic unsaturation. If an olefin copolymer, such as a low molecular weight polyisobutylene is present, it may be present in an amount of 0.1 to 3 wt. % or 0.1 to 2 wt. % or 0.2 to 2.0 wt. % of the lubricant composition.

Another material which may be present is a hydrocarbyl-substituted phenol. This may be a similar material to that used in the preparation of the Mannich dispersant, above, and its description as recited there will be applicable for this component as well. In one embodiment, the hydrocarbyl-substituted phenol may be a polyisobutylene-substituted phenol, and the polyisobutylene group may have a number average molecular weight of 300 to 3000 or 500 to 2000 or 750 to 1600 or about 1000. Derivatives of the hydrocarbyl-substituted phenol may also be used, including the reaction products of the hydrocarbyl-substituted phenol with an amine such as an alkylene polyamine, other aliphatic and aromatic mono- and polyamines, alkanolamines having one or more hydroxyl groups and mixtures thereof, or an epoxide. The hydrocarbyl phenol, if it is present, may be present, in an amount of up to 10 wt. %, such as 0.2 to 5 wt. % or 0.5 to 4 wt. % or 1.0 to 2.0 wt. % of the lubricant composition.

The lubricant composition may also contain a detergent. The detergent may be an ashless detergent or an ash containing detergent, such as a metal-containing detergent. Detergents are often overbased materials, otherwise referred to as overbased or superbased salts. These are generally single phase, homogeneous Newtonian systems characterized by a metal content in excess of that which would be present for neutralization according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. The overbased materials are prepared by reacting an acidic material (typically an inorganic acid or lower carboxylic acid, preferably carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (e.g., mineral oil, naphtha, toluene, xylene) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter such as a phenol or alcohol.

The acidic organic material will normally have a sufficient number of carbon atoms to provide a degree of solubility in oil. The amount of excess metal is commonly expressed in terms of metal ratio. The term “metal ratio” is the ratio of the total equivalents of the metal to the equivalents of the acidic organic compound. A neutral metal salt has a metal ratio of one. A salt having 4.5 times as much metal as present in a normal salt will have metal excess of 3.5 equivalents, or a ratio of 4.5.

Such overbased materials are well known to those skilled in the art. Patents describing techniques for making basic salts of alkylaromatic sulfonic acids, carboxylic acids, phenols, phosphonic acids, and mixtures of any two or more of these include U.S. Pat. Nos. 2,501,731; 2,616,905; 2,616,911; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and 3,629,109. Yet other detergents are referred to as salixarate detergents. These include overbased materials prepared from salicylic acid (which may be unsubstituted) with a hydrocarbyl-substituted phenol, such entities being linked through —CH2- or other alkylene bridges. It is believed that the salixarate derivatives have a predominantly linear, rather than macrocyclic, structure, although both structures are intended to be encompassed by the term “salixarate”. Salixarate derivatives and methods of their preparation are described in greater detail in U.S. Pat. No. 6,200,936 and PCT Publication WO 01/56968.

In certain embodiments the detergent may be an overbased sulfonate, phenate, salicylate, or salixarate detergent. In certain embodiments it may comprise an overbased calcium phenate detergent. The phenols useful in making phenate detergents can be represented by (R¹)_(a)—Ar—(OH)_(b), where R¹ is an aliphatic hydrocarbyl group of 4 to 400 or 6 to 80 or 6 to 30 or 8 to 25 or 8 to 15 carbon atoms; Ar is an aromatic group such as benzene, toluene or naphthalene; a and b are each at least one, the sum of a and b being up to the number of displaceable hydrogens on the aromatic nucleus of Ar, such as 1 to 4 or 1 to 2. There is typically an average of at least 8 aliphatic carbon atoms provided by the R¹ groups for each phenol compound. Phenate detergents are also sometimes provided as sulfur-bridged species.

While the metal salt of the phenate detergent is typically calcium, the metal compounds useful in making the basic metal salts are more generally any Group 1 or Group 2 metal compounds (CAS version of the Periodic Table of the Elements). Examples include alkali metals such as sodium, potassium, lithium, copper, magnesium, calcium, barium, zinc, and cadmium. In one embodiment the metals are sodium, magnesium, or calcium. The anionic portion of the basic metal compound can be hydroxide, oxide, carbonate, borate, or nitrate.

The ash containing detergent may be present in the lubricant composition in an amount 0.1 to 10 wt. % of the lubricant composition, or 0.5 to 5 wt. % of the lubricant composition, or even 0.8 to 2.2 wt. %. In certain embodiments a metal-containing detergent may contribute at least about 0.1 total base number, or at least 0.3 or 0.4 or 0.6 TBN to the lubricant composition, and in some embodiments up to 3 or 2 or 1 TBN. In other embodiments, the metal-containing detergent may be present in an amount to deliver at least 0.01 percent sulfated ash to the composition. The detergent may be present in an amount to deliver 0.01 to 0.12 percent sulfated ash or, alternatively, 0.05 to 0.1 percent, or even 0.06 to 0.09 percent.

The lubricant compositions of the present invention may comprise an ashless detergent. The ashless (or metal-free) detergent may comprise a basic salt of a quaternary pnictogen compound. By basic salt, it is meant that the quaternary pnictogen compound provides base number (measured as total base number TBN by ASTM D2896 and/or ASTM D4739) to the lubricating composition.

The ashless detergents differ from conventional metal-based detergents in that they are metal free or substantially metal free or contain a lower amount of metal that would be expected based on the amount of TBN that they deliver. Alternatively expressed, they do not contribute metal ions to lubricants in which they are added, or contribute less metal ions than would be expected on the amount of TBN that they deliver. In certain embodiments the detergents are metal free, although they may be mixed with other components, such as other detergents that do contain metal, while still, in themselves, being metal free. By the term “substantially metal free” is meant a detergent that contains only a contaminant or a trace amount of a metal, an amount that may in many circumstances be ignored. For instance, such a detergent may contain less than 5% or less than 3 or 1% metal by weight.

In place of some or all of the metal ion of the detergent, the materials of the present invention will contain one or more quaternary non-metallic pnictogen cations. Pnictogens are the elements in column 15 (or Group Va) of the periodic table, the column headed by nitrogen. The non-metallic pnictogens include nitrogen and phosphorus.

Quaternary nitrogen or phosphorus compounds are known. Ordinarily nitrogen is a trivalent element, forming three covalent bonds to hydrogen or carbon atoms in ammonia or amines: NH_(x)R_(3-x), where R is a group linked to the nitrogen atom through a carbon atom of the R group. Quaternary nitrogen compounds, on the other hand, comprise a quaternary ammonium ion and a counterion (e.g., hydroxide, halide), represented by the general formula

NR₄ ⁺X⁻

where, each R independently represents a suitable hydrocarbyl group, and X⁻ represents one equivalent of an anionic counterion, which may include fractional equivalents of polyanionic species (e.g. a half mole of carbonate, i.e. ½ CO²⁻). Quaternary phosphonium ions may be similarly represented (PR₄ ⁺). In such materials, the nitrogen (or phosphorus) has four substantially non-ionizable covalent bonds to carbon atoms. The quaternary atoms are permanently charged and are comparatively unaffected by the pH of the medium. They are thus distinguished from ordinary ammonium or phosphonium ions or protonated amines, which materials contain up to three substantially non-ionizable covalent bonds to carbon and one or more acidic hydrogen atoms or protons associated with the nitrogen or phosphorus atom. The present quaternary ions will not contribute acidity to the detergent, as would be titratable as TAN by ASTM D 664A. The basic ashless detergents of the present technology will thus be free from acidic protons in the sense that they will have the general structure NR₄ ⁺X⁻ rather than HNR₃ ⁺X⁻, in the case of nitrogen. However, the detergent molecules overall may (or may not) contain other acidic hydrogen that is titratable as TAN, on other portions of the detergent than the cation, that is, on the anionic substrate portion. An example of a titratable hydrogen might be on a phenolic OH group or bicarbonate (HCO₃ ⁻). In certain embodiments, however, the detergent as a whole will be substantially free from acidic protons, having a TAN of less than 10 or less than 5 or less than 3 or less than 1, on an oil free basis.

It is not intended that each of the four bonds of the nitrogen or phosphorus must necessarily be directed to a separate carbon atom: The 4 R groups are not necessary different carbon groups. Thus two of the bonds may be directed to the same carbon atom in a double-bonded structure or as delocalized bonds within an aromatic ring. Examples of such include pyridinium ions and imidazolium ions.

Many quaternary salt compounds are known. Quaternary ammonium salts, for instance, are commercially available and may be prepared by the reaction of ammonia or an amine with an alkyl halide as the complete alkylation product. Certain quaternary phosphonium salts may be prepared by the reaction of phosphine with aldehydes, e.g., tetrakis(hydroxymethyl)phosphonium chloride. Examples of quaternary ammonium compounds include tetrahydrocarbyl ammonium salts with hydrocarbyl groups such as methyl, ethyl, propyl, butyl, benzyl, and mixtures thereof. In another embodiment, up to three of the R groups in the quaternary NR₄ ⁺ structure may be such hydrocarbyl groups and one or more groups may be a hydroxy-substituted hydrocarbyl group such as a hydroxyalkyl group, or an amine-substituted hydrocarbyl group. Examples of quaternary ammonium salts containing a hydroxyalkyl group, and methods for their synthesis, are disclosed in U.S. Pat. No. 3,962,104, Swietlik et al.; see column 1 line 16 through column 2 line 49; column 8 lines 13 through 49, and the Examples. In certain embodiments, the quaternary ammonium compound is derived from a monoamine, i.e. a tertiary amine having only a single amino group, i.e. having no additional amine nitrogen atoms in any of the three hydrocarbyl groups or substituted hydrocarbyl groups attached to the tertiary amine nitrogen. In certain embodiments there are no additional amine nitrogen atoms in any of the hydrocarbyl groups or substituted hydrocarbyl groups attached to the central nitrogen in the quaternary ammonium ion. Further examples of quaternary ammonium compounds include tetraethylammonium hydroxide or halide and tetrabutylammonium hydroxide or halide and such biological materials as choline chloride, HOCH₂CH₂N(CH₃)₃Cl. Any such materials may provide the cation for the present detergents.

The anion portion of the detergent may be an organic anion having at least one aliphatic hydrocarbyl group of sufficient length to impart oil solubility to the detergent. Suitable aliphatic hydrocarbyl groups, if they are in the form of a substituent on an aromatic ring (as in alkylphenates or alkylbenzenesulfonates) may contain 4 to 400 carbon atoms, or 6 to 80 or 6 to 30 or 8 to 25 or 8 to 15 carbon atoms. The anionic portion of the detergent may thus be any of the anions derived from the acidic organic materials that are used to prepare conventional detergents. As mentioned above, these include sulfonic acids, providing sulfonate detergents with sulfonate anions, carboxylic acids, providing carboxylate detergents with carboxylate anions, phenols, providing phenate detergents with phenate anions, hydrocarbyl-substituted salicylic acids, providing salicylate detergents with salicylate anions, phosphonic acids, providing phosphonate detergents, as well as salixarate, calixarate, and saligenin detergents, and mixtures thereof. In certain embodiments the ashless detergents may be sulfonates or salicylates, and in other embodiments, sulfonates.

The anion portion of the ashless detergent may be an acylated (co)polymer.

Acylated (co)polymers include (co)polymers containing or functionalized with at least one carboxylic acid group, carboxylic anhydride, or mixtures thereof. Acylated polymers include polyolefins that have been grafted or otherwise functionalized with one or more α,β-unsaturated acylating agents. Suitable polyolefins include (co)polymers of ethylene, propylene, butene, isobutylene, higher alpha-olefins, butadiene, isoprene, and combinations thereof. In one embodiment, the acylated copolymer is a polyisobutylene having a number average molecular weight (Mn) of 400 to 3000 (as measured versus polystyrene standards) functionalized with at least 1 and up to 2 succinic acid groups or functional equivalents (e.g. succinic anhydride). In one embodiment, the acylated copolymer is a copolymer of ethylene and at least one higher alpha olefin, wherein the olefin copolymer has Mn of between 5000 Daltons and 100,000 Daltons or between 15,000 Daltons and 60,000 Daltons (as measured by GPC against polystyrene standards). In one embodiment, the acylated copolymer is a copolymer of ethylene and propylene; a copolymer of ethylene, propylene and butene; a copolymer of ethylene and butene; or combinations thereof.

The acylated copolymer may be a poly(meth)acrylate (PMA) containing at least one of (meth)acrylic acid moieties, other acylated monomers that copolymerize readily with (meth)acrylates, or combinations thereof. In one embodiment, the poly(meth)acrylate contains at least 2 weight percent (meth)acrylic acid moiety, either by direct incorporation of (meth)acrylic acid monomers during polymerization or by partial hydrolysis of the polymethacrylate after polymerization is complete. PMA's are prepared from mixtures of methacrylate monomers having different alkyl groups. The alkyl groups may be either straight chain or branched chain groups containing from 1 to 24 carbon atoms. Other acylated monomers that may co-polymerize with (meth)acrylates include maleic acid, maleic anhydride, fumaric acid, cinnamic acid, caffeic acid, esters of the preceding acids, and combinations thereof.

The anion portion of the ashless detergent may further include an inorganic anion, especially the conjugate base of inorganic protic acids. Inorganic anions include borate, sulfate, phosphate, nitrate, carbonate, bicarbonate, hydroxide, and combinations thereof. In one embodiment, the ashless detergent comprises a quaternary pnictogen salt of an inorganic base such as carbonate, bicarbonate, hydroxide, or mixtures thereof.

The ashless quaternary pnictogen detergent may be a mixture of both organic and inorganic anions salts; that is, the quaternary pnictogen cation would be present in excess of the amount necessary to effect a stoichiometric neutral salt with the organic anion. In such cases, the ashless detergent may be understood to be overbased. Degree of overbasing (or “base ratio”) can be calculated as the ratio of cation equivalents (herein described as a quaternary pnictogen cation) to organic anion equivalents; a neutral salt of [tetraalkylammonium] [alkylbenzenesulfonate] can be seen as having a base ratio of 1.0. In one embodiment, the ashless detergent comprising a quaternary pnictogen salt of an organic anion is overbased. The ashless detergents of the present invention may thus, in certain embodiments, have a base ratio of 1.1, 1.5 or 2 or 3 or 7, up to 40 or 25 or 20 or 10.

Overbased ashless detergents may be obtained by a process analogous to the process for preparing overbased metal-containing detergents, while considering the important differences required to obtain the present materials. That is, the present detergents may be prepared by reacting a mixture comprising an acidic organic compound or substrate, as described above, with a molar excess, that is, a stoichiometric excess, of a basic quaternary pnictogen compound, optionally in an inert reaction medium or organic solvent such as mineral oil, naphtha, toluene, or xylene. Optionally an additional acidic material may be present, such as oxo acid, e.g., carbon dioxide, to form a carbonate or bicarbonate, and optionally a small amount of a promoter (e.g. an alkanol of one to twelve or one to six carbon atoms such as methanol, ethanol, or amyl alcohol, or an alkylated an alkylated phenol such as heptylphenol, octylphenol, or nonylphenols) may be present.

The presence of the oxo acid may assist in incorporation of larger quantities of base, through formation of, in the case of carbon dioxide, colloidal carbonate of the base. Suitable oxo anions which may become a part of the overbased detergent include carbonate, bicarbonate, borate, hydroxide, nitrate, phosphate, sulfate, and carboxylate, such as oxalate, tartrate, citrate, succinate, and acetate ions. The carboxylate anions may contain 8 or fewer or 6 or fewer or 5 or fewer or 3 or 2 or 1 carbon atom(s). Also included may be ions derived from β-keto esters and diketones. The oxo anions may be derived from inorganic acids, e.g., carbonate or bicarbonate ions.

In one embodiment, the ashless detergent may at least one of an alkylbenzene sulfonate detergent, a phenate detergent, a sulfur-coupled detergent, a salicylate detergent, an aliphatic carboxylic acid detergent, overbased compositions of said detergents, or mixtures thereof.

The ashless detergent may have a TBN of at least 35 mg KOH/g as measured by ASTM D2896. In one embodiment the ashless detergent may have a TBN of at least 50 mg KOH/g, or at least 75 mg KOH/g, or at least 95 mg KOH/g (reported on an oil-free basis, i.e., excluding any diluent oil).

The ashless detergent may be present in the lubricant composition in an amount 0.1 to 10 wt. % of the lubricant composition, or 0.5 to 5 wt. % of the lubricant composition, or even 0.8 to 2.2 wt. %. In some embodiments, the ashless quaternary pnictogen detergent may be present in the lubricating composition in amount to deliver total base number (TBN) at least 1.5 mg KOH/g to the composition, or at least 2.3, or 3.0 up to 12, or even 4.4 up to 8.5 mg KOH/g to the lubricating composition (as measured by ASTM D2896).

The total amount of the detergent, if present, may in certain embodiments be up to 10 wt. % or 5 wt. % e.g., 0.01 to 5 wt. % or 0.01 to 3 wt. % or 0.5 to 3 wt. % or 0.5 to 2.0 wt. %.

In certain embodiments, the present lubricant composition is not an ash-free lubricant; that is, the detergent may be an ash-containing detergent, containing 0.01 to 0.12 percent sulfated ash or, alternatively, 0.05 to 0.1 percent, or even 0.06 to 0.09 percent, which ash may be provided by the metal-containing detergent or detergents or in whole or in part from other sources such as zinc salts (e.g., zinc dialkyldithiophosphates), molybdenum compounds, or titanium compounds.

In some embodiments of the present invention, mixtures of ash containing and ashless detergents may be employed. In some embodiments, the lubricant composition may be substantially free of ashless detergents. In yet other embodiments, the lubricant composition may be substantially free of ash-containing detergents.

A further component of the present lubricant compositions may include a surfactant, in an amount up to about 5 wt. % or up to about 4 wt. % or from about 0.05 to about 5 wt. % or about 0.05 to about 4 wt. %. The surfactant may comprise an oil soluble polyalkylene glycol, which may be a homopolymer or a copolymer, typically a copolymer.

The lubricant composition may include a polyether fluidizer component comprising a polyether, a polyetheramine, or mixtures thereof. The polyether of the present invention can be represented by the formula RO[CH₂CH(R¹)O]_(x)H where R is a hydrocarbyl group; R¹ is selected from the group consisting of hydrogen, alkyl groups of 1 to 14 carbon atoms, and mixtures thereof; and x is a number from 2 to 50. The hydrocarbyl group R is a univalent hydrocarbon group, has one or more carbon atoms, and includes alkyl and alkyl-phenyl groups having 7 to 30 total carbon atoms, such as 9 to 25 total carbon atoms, or 11 to 20 total carbon atoms. The repeating oxyalkylene units may be derived from ethylene oxide, propylene oxide, or butylene oxide. The number of oxyalkylene units x may be 10 to 35, or 18 to 27. The polyether of the present invention can be prepared by various well-known methods including condensing one mole of an alcohol or alkylphenol with two or more moles of an alkylene oxide, mixture of alkylene oxides, or with several alkylene oxides in sequential fashion, usually in the presence of a base catalyst. U.S. Pat. No. 5,094,667 provides reaction conditions for preparing a polyether. Suitable polyethers are commercially available from Dow Chemicals, Huntsman, ICI and include the Actaclear® series from Bayer.

The polyetheramine of the present technology can be represented, in certain embodiments, by the formula R[OCH₂CH(R¹)]_(n)A, where R is a hydrocarbyl group as described above for polyethers; R¹ is selected from the group consisting of hydrogen, alkyl groups of 1 to 14 carbon atoms, and mixtures thereof; n is a number from 2 to 50; and A is selected from the group consisting of —OCH₂CH₂CH₂NR²R² and —NR³R³ where each R² is independently hydrogen or a hydrocarbyl group of one or more carbon atoms, and each R³ is independently hydrogen, a hydrocarbyl group of one or more carbon atoms, or —[R⁴N(R⁵)]_(p)R⁶ where R⁴ is C₂-C₁₀ alkylene, R⁵ and R⁶ are independently hydrogen or a hydrocarbyl group of one or more carbon atoms, and p is a number from 1 to 7. The polyetheramine may be derived from ethylene oxide, propylene oxide, or butylene oxide. The number of oxyalkylene units n in the polyetheramine may be 10 to 35, or 18 to 27. The polyetheramine of the present technology can be prepared by various well known methods. A polyether derived from an alcohol or alkylphenol as described above can be condensed with ammonia, an amine or a polyamine in a reductive amination to form a polyetheramine as described in European Publication No. EP 310875. Alternatively, the polyether can be condensed with acrylonitrile and the nitrile intermediate hydrogenated to form a polyetheramine as described in U.S. Pat. No. 5,094,667. Suitable polyetheramines include those where A is —OCH₂CH₂CH₂NH₂. Polyetheramines are commercially available in the Techron® series from Chevron and in the Jeffamine® series from Huntsman.

In one embodiment, the polyether may be represented by the formula R¹—(—O—R²—)_(n)—R³ wherein R¹ is a hydrocarbyl group of 10 to 24 (or 12 to 15) carbon atoms, each R² is independently an alkylene group of 2 to 6 (or 3 to 4) carbon atoms, n is 10 to 30 (or 18 to 26), and R³ is H or an alkyl group or —CH₂CH₂NH₂ or —CH₂CH₂CH₂NH₂ or —CH₂CHRNH₂, where R is an alkyl group (especially, methyl or ethyl), e.g., —CH₂CH(CH₃)NH₂, or where together R¹ and R³ may represent an alkylene group so as to form a cyclic ether. A suitable polyether, which may also be described as a polyether fluidizer, may comprise a reaction product of one unit of (that is, derived from) a hydroxy-containing hydrocarbon and two or more units of (that is, derived from) an alkylene oxide, wherein the hydroxy-containing hydrocarbon contains 1 to 50 carbon atoms and the alkylene group of the alkylene oxide contains 2 to 6 carbon atoms, wherein the reaction product is optionally further reacted with acrylonitrile and hydrogenated to provide a terminal amino group.

The polyether or polyetheramine of the present technology may have a number average molecular weight of 300 or 350 to 5000, in another instance of 400 to 3500, and in further instances of 450 to 2500 and 1000 to 2000.

The polyether (or polyether fluidizer) may be present in the lubricant composition in an amount of 0.01 or 0.05 or 0.1 or 0.3 or 0.5 to 5 wt. %, or 0.8 to 4 wt. % or 1 to 3 wt. % or 0.1 to 3 wt. % or 1.5 to 2.5 wt. %, e.g., about 2 wt. %

Other conventional components may also be present, including pour point depressants; viscosity index modifiers; metal deactivators; antioxidants; rust inhibitors, corrosion inhibitors, high pressure additives, anti-wear additives, and antifoam agents. Any of these materials can be present or can be eliminated, if desired.

The lubricant compositions formed as described above may, in some embodiments comprise only ash-free components, and thus be characterized as ash-free lubricant compositions. In other embodiments, one or more components may contribute ash to the lubricant composition. The total ash content of the lubricant composition may be less than 2000 parts per million (ppm) or less than 1500 ppm, or 1000 ppm, or 500 ppm, or 250 ppm or 100 ppm.

The lubricant compositions may have a sulfur content of less than 500 ppm or 400 ppm or 200 ppm or 100 ppm. In some embodiments, the lubricant composition may be substantially free of sulfur containing components.

The components of the present invention can be prepared by mixing the indicated components directly, or by preparing one or more of the components in the form of a concentrate, to which other components (such as oil or solvent) can subsequently be added.

The present lubricant may be supplied to an engine in any of a variety of ways, depending at least in part on the design of the engine. It may be supplied along with the fuel, either by injection into the fuel stream or by premixing the lubricant into the bulk fuel.

Regarding the fuel, any of a variety of fuels may be used. The fuel is normally a liquid at ambient conditions e.g., room temperature (20 to 30° C.). The fuel may be a hydrocarbon fuel, a nonhydrocarbon fuel, or a mixture thereof. The fuel into which the lubricant composition for a two-cycle engine is mixed is commonly, but not necessarily, gasoline as defined by ASTM specification D4814. In one embodiment, the fuel is a gasoline, and in other embodiments, the fuel is a leaded gasoline or a nonleaded gasoline. The nonhydrocarbon fuel can be an oxygen-containing composition, often referred to as an oxygenate, which can include an alcohol, an ether, a ketone, an ester of a carboxylic acid, a nitroalkane, or a mixture thereof. The nonhydrocarbon fuel can include, for example, methanol, ethanol, propanol, butanol, methyl t-butyl ether, methyl ethyl ketone, transesterified oils and/or fats from plants and animals such as rapeseed methyl ester and soybean methyl ester, and nitromethane. In some embodiments, the fuel can have an oxygenate content on a weight basis of 15 percent by weight, or 25 percent by weight, or 50 percent by weight, or 65 percent by weight, or 85 percent by weight, or 90 percent by weight. Mixtures of hydrocarbon and nonhydrocarbon fuels can include, for example, gasoline and methanol and/or ethanol, diesel fuel and ethanol, and diesel fuel and a transesterified plant oil such as rapeseed methyl ester, fuels referred to as E85 or M85, and fuels referred to as AlCool™. In one embodiment, mixtures of hydrocarbon and nonhydrocarbon fuels can be defined by ASTM D-5798-99. In one embodiment, the fuel comprises a blend of ethanol and gasoline having a ratio from 10:90 to 90:10, or 15:85 to 90:10, or 25:75 to 90:10. In an embodiment, the fuel can be an emulsion of water in a hydrocarbon fuel, in a nonhydrocarbon fuel, or a mixture thereof. The lubricant may be blended into the liquid fuel in an amount or ratio of 1:200 to 1:25 by volume, or 1:60 to 1:40, or about 1:50 (e.g., about 2% lubricant by volume). In certain embodiments of the present inventions, the lubricant composition, when blended into the liquid fuel in an amount or ratio of about 1:50, delivers a base oil to liquid fuel ratio of about 1:125 to 1:500, or 1:150 to 1:400, or 1:200 to 1:350 by volume.

It is accordingly within the scope of the present technology to provide a combustible mixture for fueling an engine, such as a two cycle engine, that comprises a lubricant composition as described admixed with a liquid fuel at a ratio of 1:60 to 1:40, or about 1:50 by volume.

In combustible mixtures of the present technology, the ratio of the oil of lubricating viscosity to liquid fuel may be 1:125 to 1:500, or 1:150 to 1:400, or 1:200 to 1:350 by volume, while demonstrating excellent performance and reduced particulate matter in at least one of total particulate mass, particulate number, total organic carbon or elemental carbon, or particulate size.

The lubricant and/or the combustible mixture formed using the lubricant composition of the present technology may be profitably employed in a two-stroke cycle engine. Such engines are commonly used in lawn and garden equipment, portable contractor equipment such as pumps and electrical generators, low-cost transportation vehicles, such as mopeds, as well as commercial and recreational vehicles including motorcycles, outboard engines (for boats and marine vehicles), snowmobiles, and personal watercraft vehicles. In some larger recreational applications as in outboard engines, engines with a displacement of 2,000 to 3,000 cm³ generate approximately 150 kW (201 hp). 2-stroke cycle engines can also be found in very small applications, such as in power tools like weed trimmers or chain saws. These smaller engines typically output up to 10 hp or up to 5 hp or 1 to 10 hp or 1 to 5 hp or 5 to 10 hp. The engine may have a cylinder displacement of 20 to 80 cm³. In some embodiments, therefore, the engines may have a power output of less than 150 kW, such as less than 100 or less than 50 or less than 20 kW; or 0.1 to 15 kW or 0.5 to 10 kW or 1-5 kW, and optionally a cylinder displacement of 10 to 300 cm³, or 15-100 or 20-80 cm³.

The amount of each chemical component described is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, that is, on an active chemical basis, unless otherwise indicated. However, unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade.

It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. For instance, metal ions (of, e.g., a detergent) can migrate to other acidic or anionic sites of other molecules. The products formed thereby, including the products formed upon employing the composition of the present invention in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present invention; the present invention encompasses the composition prepared by admixing the components described above.

Examples

A series of lubricant compositions is prepared according to the formulations in Table 1 and tested in a Stihl FS 460C two-stroke cycle brush cutter engine, 45.6 cm³ engine displacement, running on gasoline-lubricant mixtures (1:50 admixture of lubricant and fuel (unadditized gasoline)). Preparation of the engine for each test involves draining (as necessary) any existing fuel/oil mixture and replacing the fuel filter. A portion of the fuel/oil candidate is run in the engine at idle for 15 minutes followed by a wide open throttle for 15 minutes. The remaining fuel/oil is drained and the fuel filter is again changed. A new portion of the fuel/oil mixture is then put into the engine in preparation for the test.

The test consists of two stages: an idle portion and a full throttle portion. The engine is operated at the idle condition for 15 minutes. During the last 5 minutes, data on emissions from the engine is collected. The engine is then operated at the full throttle condition for 15 minutes. During the last 5 minutes, data on emissions from the engine is collected. This idle/full throttle sequence is repeated four times (for a total of five data collections in each of idle and full throttle operation).

Collection of particulates was undertaken employing a device similar to the Solid Particle Sampling System described in SAE Technical Paper No. 2007-01-0307, entitled “Sampling System for Solid and Volatile Exhaust Particle Size, Number and Mass Emissions”. For purposes of the particulate collection herein, the Solid Particle Sampling System was dissimilar to the system described in the referenced SAE Technical Paper in that the 2T engine exhaust was coupled to a full-flow dilution tunnel, instead of a micro-dilution tunnel as depicted. Particle mass was measured using a Sierra BG3 partial flow sampling system from Sierra Instruments, Inc. Particle number and size were measured using a TSI Engine Exhaust Particle Sizer (EEPS) available from TSI.

Particulate matter was evaluated with respect to total particulate mass and particulate number.

TABLE 1 Amounts, % by weight* Comp 1 Ex 1 Ex 2 Ex 3 Oil^(a) Balance to Balance Balance Balance to 100% to 100% to 100% 100% Solvent^(b) — 66.67 80.00 80.00 Polyolefin-substituted phenol 2.00 0.67 0.40 2.00 Friction Modifier (GMO) 0.50 0.17 0.10 0.50 Mannich dispersant^(c) 1.91 0.64 0.38 1.91 Succinimide dispersant^(d) 1.91 0.64 0.38 1.91 *on an oil free basis. ^(a)Base oil plus diluent oils from other additives. ^(b)Exxsol D-80 aliphatic hydrocarbon solvent from Exxon. ^(c)Product of polyisobutylene phenol, formaldehyde, and dimethylamine. ^(d)4.7% N content.

The results depicted in Graphs 1 and 2 demonstrate that the lubricant formulas of the disclosed technology provided fuel lubricant compositions that operated the exemplary two-cycle engines with a significant reduction in both overall mass of particle emissions and total particle number. The same was achieved with no noticeable reduction in engine performance, cleanliness, or power output.

Each of the documents referred to above is incorporated herein by reference. The mention of any document is not an admission that such document qualifies as prior art or constitutes the general knowledge of the skilled person in any jurisdiction. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word “about”. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention can be used together with ranges or amounts for any of the other elements. As used herein, the expression “consisting essentially of” permits the inclusion of substances that do not materially affect the basic and novel characteristics of the composition under consideration. As used herein, the expression “substantially free of” means that none of the described materials is intentionally present, but does not exclude small or trace amounts present due to its presence in other materials as an impurity and/or byproduct.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include hydrocarbon substituents, including aliphatic, alicyclic, and aromatic substituents; substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent; and hetero substituents, that is, substituents which similarly have a predominantly hydrocarbon character but contain other than carbon in a ring or chain. A more detailed definition of the term “hydrocarbyl substituent” or “hydrocarbyl group” is found in paragraphs [0137] to [0141] of published application US 2010-0197536. 

1. A lubricating composition comprising: (a) 5 to 35 wt. % of an oil of lubricating viscosity; (b) 50 to 90 wt. of a hydrocarbon solvent; and (c) at least one additive selected from (i) a dispersant and (ii) a friction modifier.
 2. The lubricating composition of claim 1, wherein the composition comprises a friction modifier and a dispersant.
 3. The lubricating composition of claim 2, comprising from about 0.2 to 10 wt. %, of the dispersant.
 4. The lubricating composition of claim 2, wherein the dispersant is selected from a phenolic-type dispersant, a Mannich-type dispersant or a succinimide-type dispersant or mixtures thereof.
 5. The lubricating composition of claim 2, wherein the dispersant comprises: (a) a Mannich-type dispersant; and (b) a succinimide-type dispersant.
 6. The lubricating composition of claim 2, wherein the dispersant further comprises a phenolic-type dispersant.
 7. The lubricating composition of claim 2, wherein the dispersant is ashless.
 8. The lubricating composition of claim 2, wherein the weight percent ratio of dispersant to oil of lubricating viscosity is 1:6 to 1:2.5.
 9. The lubricating composition of claim 1, comprising from 0.1 to 5 wt. % of a friction modifier.
 10. The lubricating composition of claim 1, wherein the friction modifier comprises at least one of fatty phosphites, fatty acid amides, fatty epoxides, borated fatty epoxides, fatty amines, glycerol esters, borated glycerol esters, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, sulfurized olefins, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines, amide, ester or imide derivatives of hydroxy-carboxylic acids, metal salts of alkyl salicylates, amine salts of alkylphosphoric acids and mixtures thereof.
 11. The lubricating composition of claim 1, wherein the friction modifier is an ash-free friction modifier and is substantially free of ash containing friction modifier.
 12. The lubricating composition of claim 1, wherein the friction modifier is an ash-containing friction modifier and is substantially free of ash-free friction modifier.
 13. The lubricating composition of claim 1, wherein the friction modifier is an ester, amide or imide derivative of an alpha-hydroxy carboxylic acid.
 14. The lubricating composition of claim 1 further comprising a detergent.
 15. The lubricating composition of claim 1, wherein the detergent is an ash containing detergent and is substantially free of ash-free detergent.
 16. The lubricating composition of claim 1, wherein the detergent is an ashless detergent and is substantially free of ash containing detergent.
 17. The lubricating composition of claim 1, wherein the detergent is present in an amount from 0.01 to 5 wt. %.
 18. The lubricating composition of claim 1, having an ash content of less than 2000 ppm.
 19. The lubricating composition of claim 1, wherein the lubricating composition is substantially free of ash.
 20. The lubricating composition of claim 1, having a sulfur content of less than 500 ppm.
 21. The lubricating composition of claim 1, wherein the composition is substantially free of sulfur.
 22. The lubricating composition of claim 1 wherein the oil of lubricating viscosity comprises a Group IV or V base oil or mixture thereof.
 23. The lubricating composition of claim 1, wherein the oil of lubricating viscosity comprises a synthetic ester oil.
 24. The lubricating composition of claim 1, wherein the hydrocarbon solvent is selected from the group consisting of aromatic type hydrocarbon solvents, aliphatic type hydrocarbon solvents, naphthenic type hydrocarbon solvents and blends thereof.
 25. The lubricating composition of claim 1, wherein the hydrocarbon solvent comprises a naphthenic type hydrocarbon solvent.
 26. The lubricating composition of claim 1, wherein the hydrocarbon solvent comprises an aromatic type hydrocarbon solvent.
 27. The lubricating composition of claim 1, wherein the hydrocarbon solvent comprises an aliphatic type hydrocarbon solvent.
 28. A method of lubricating an engine comprising a combustion chamber, the method comprising the step of supplying to the combustion chamber a lubricating composition of claim
 1. 29. The method of claim 28, wherein the engine is a two-cycle engine.
 30. The method of claim 28, wherein the lubricating composition is admixed with a major amount of a liquid fuel composition, and the resulting admixture is supplied to the combustion chamber.
 31. The method of claim 30, wherein the lubricating composition is admixed with the liquid fuel composition at a ratio of 1:200 to 1:25 by volume.
 32. The method of claim 31, wherein the ratio of the oil of lubricating viscosity to liquid fuel in the admixture is 1:125 to 1:500.
 33. The method of claim 26, wherein the engine comprises a carburetor.
 34. The method of claim 26, wherein a portion of the lubricating composition is supplied to the combustion chamber by direct injection, port fuel injection, or throttle body injection.
 35. The method of claim 26, wherein the engine has a peak power output of about 10 horsepower (7.46 kW)
 36. A combustible mixture for fueling a two-cycle engine comprising a lubricating composition admixed with a liquid fuel composition at a ratio of 1:60 to 1:40 by volume, wherein the lubricating composition comprises: a. from 5 wt. % to 35 wt. % of an oil of lubricating viscosity; b. from 60 wt. % to 90 wt. of a hydrocarbon solvent; c. from 0.02 wt. % to 10 wt. % of a dispersant; d. from 0.1 wt. % to 5 wt. % of at least one friction modifiers; and e. optionally, a detergent.
 37. The combustible mixture of claim 36, wherein the dispersant comprises (a) a Mannich-type dispersant; and (b) a succinimide-type dispersant.
 38. The combustible mixture of claim 36, wherein the weight percent ratio of dispersant to oil of lubricating viscosity is 1:6 to 1:2.5.
 39. The combustible mixture of claim 36, wherein the ratio of the oil of lubricating viscosity to liquid fuel in the admixture is 1:125 to 1:500 by volume.
 40. A method of fueling a two-cycle engine comprising a combustion chamber, the method comprising the step of supplying to the combustion chamber a combustible mixture of claim
 36. 